Compressor and Hot Section Fouling in Gas Turbines- Causes and Effects

Abstract

The fouling of axial flow compressors and turbines is a serious operating problem in gas turbine engines. These prime movers are being increasingly used in cogeneration applications and with the large air mass flow rate (e.g. 633 Lbs/Sec for a 80 MWe gas turbine) foulants even in the ppm range can cause deposits on the blading resulting in severe performance decrements. This is a common operating problem experienced by almost all operators of gas turbines. The effect of compressor fouling is a drop in airflow and a drop in compressor isentropic efficiency. Fouling of the axial compressor results in a drop in output and thermal efficiency of the system. In some cases, fouling can also result in surge problems as its effect is to move the compressor surge line to the right i.e. towards the operating line. This paper discusses the mechanism of fouling and the aerodynamic and thermodynamic effects. This paper also discusses types of foulants commonly experienced, detection methods and filtration techniques. A brief discussion of turbine fouling, which is particularly relevant when heavy fuels are utilized, is also discussed.